// Copyright 2011 The Go Authors.  All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//package tree // import "golang.org/x/tour/tree"
package tree

import (
    "fmt"
    "math/rand"
)

// A Tree is a binary tree with integer values.
type Tree struct {
    Left  *Tree
    Value int
    Right *Tree
}

// New returns a new, random binary tree holding the values k, 2k, ..., 10k.
func New(k int) *Tree {
    var t *Tree
    for _, v := range rand.Perm(10) {
        t = insert(t, (1+v)*k)
    }
    return t
}

func insert(t *Tree, v int) *Tree {
    if t == nil {
        return &Tree{nil, v, nil}
    }
    if v < t.Value {
        t.Left = insert(t.Left, v)
    } else {
        t.Right = insert(t.Right, v)
    }
    return t
}

func (t *Tree) String() string {
    if t == nil {
        return "()"
    }
    s := ""
    if t.Left != nil {
        s += t.Left.String() + " "
    }
    s += fmt.Sprint(t.Value)
    if t.Right != nil {
        s += " " + t.Right.String()
    }
    return "(" + s + ")"
}
